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BUREAU OF MINES 
INFORMATION CIRCULAR/1990 

1^3 




Fuel Additive and Engine Operation 
Effects on Diesel Soot Emissions 



By H. William Zeller 




BUREAU OF MINES 
1910-1990 

THE MINERALS SOURCE 



Mission: Asthe Nation's principal conservation 
agency, the Department of the Interior has respon- 
sibility for most of our nationally-owned public 
lands and natural and cultural resources. This 
includes fostering wise use of our land and water 
resources, protecting our fish and wildlife, pre- 
serving the environmental and cultural values of 
our national parks and historical places, and pro- 
viding for the enjoyment of life through outdoor 
recreation. The Department assesses our energy 
and mineral resources and works to assure that 
their development is in the best interests of all 
our people. The Department also promotes the 
goals of the Take Pride in America campaign by 
encouraging stewardship and citizen responsibil- 
ity for the public lands and promoting citizen par- 
ticipation in their care. The Department also has 
a major responsibility for American Indian reser- 
vation communities and for people who live in 
Island Territories under U.S. Administration. 



Information Circular 9238 



Fuel Additive and Engine Operation 
Effects on Diesel Soot Emissions 



By H. William Zeller 



UNITED STATES DEPARTMENT OF THE INTERIOR 
Manuel Lujan, Jr., Secretary 

BUREAU OF MINES 
T S Ary, Director 



c\$ 






Library of Congress Cataloging in Publication Data: 



Zeller, H. William. 

Fuel additive and engine operation effects on diesel soot emissions / by H. 
William Zeller. 

p. cm. - (Information circular / Bureau of Mines; 9238) 

Includes bibliographical references. 

Supt. of Docs, no.: I 28.27:9238. 

1. Mining machinery-Motors (Diesel)-Safety measures. 2. Diesel motor exhaust 
gas-Purification. 3. Diesel fuels-Additives. 4. Barium. I. Title. II. Series: 
Information circular (United States. Bureau of Mines); 9238. 

TN295.U4 [TN345] 622 s-dc20 [622'.6] 89-600302 

CIP 



CONTENTS 

Page 

Abstract 1 

Introduction 2 

Acknowledgments 2 

Apparatus and procedures 2 

Engine test conditions 3 

Fuel, oil, and additive mixing 4 

Emissions measurement 4 

Results and analysis 4 

Particulate emissions 4 

Diesel particulate matter 4 

Untreated fuel 4 

Beu"ium-treated fuel 6 

Solid particulate fraction 6 

Volatile particulate fraction 6 

Comparison of solid and volatile fractions 10 

Hydrocarbon emissions 11 

Gaseous hydrocarbons 11 

Total exhaust hydrocarbons 12 

Toxic gaseous emissions 12 

Nitrogen oxides 12 

Carbon monoxide , . 14 

Engine comparison 14 

Conclusions and recommendations 16 

References 16 

Appendix-Additive specifications 17 

ILLUSTRATIONS 

1. Diesel engine emissions research laboratory 3 

2. DPM emissions from Deutz engine for untreated fuel, 2,300 r/min, and medium intake restriction 4 

3. DPM emissions from Deutz engine for untreated fuel, full load, four speeds, and three intake 

restrictions 5 

4. DPM emissions from Deutz engine as function of fuel-air ratio for untreated fuel 5 

5. Effect of barium fuel additive on DPM constituents from Caterpillar engine at 1,200 r/min 7 

6. Effect of additive concentration on DPM emissions from Deutz engine at two speeds and 25, 90, and 

100 pet of full load 7 

7. Additive effect on DPM emissions from Deutz engine at different fuel-air ratios 8 

8. SDPM emissions from Deutz engine for untreated fuel 8 

9. Additive effect on SDPM emissions from Deutz engine at 80 pet of rated speed 9 

10. VDPM emissions from Deutz engine for untreated fuel 9 

11. Additive effect on VDPM from Deutz engine at full speed 10 

12. Comparison of soHd and volatile particulates from Deutz engine at full speed for small intake 

restriction , 10 

13. GPHC concentrations from Deutz engine for untreated fuel 11 

14. GPHC concentrations for different additive concentrations and for all Deutz engine conditions 12 

15. TEHC concentrations for untreated fuel and all Deutz engine conditions 13 

16. TEHC concentrations from Deutz engine for treated fuel at full speed 13 

17. Comparison of nitrogen oxide concentrations from Deutz engine for treated and untreated fuels 14 

18. Comparison of carbon monoxide concentrations from Deutz engine for treated and untreated fuels .... 15 

19. Comparison of DPM from Deutz and Caterpillar engines for untreated fuel 15 

20. Comparison of DPM from Deutz and Caterpillar engines for treated fuel 15 





UNIT OF MEASURE ABBREVIATIONS USED IN THIS REPORT 


atm 


atmosphere, standard 


L 


liter 


"C 


degree Celsius 


lb 


pound 


cfm/hp 


cubic foot per minute 
per horsepower 


mg/hp-min 


milligram per horsepower-minute 


cSt 


centistokes 


mg/m' 


milligram per cubic meter 


op 


degree Fahrenheit 


mg/min 


milligram per minute 


gal 


gallon 


pet 


percent 


h 


hour 


r/mrn 


revolution per minute 


hp 


horsepower 


vol pet 


volume percent 


in HP 


inch of water 


wt pet 


weight percent 



FUEL ADDITIVE AND ENGINE OPERATION EFFECTS 
ON DIESEL SOOT EMISSIONS 



By H. William Zeller^ 



ABSTRACT 

The Bureau of Mines performed laboratory research into the effects of a barium-based fuel additive 
(the "postflame" type) on diesel particulate matter (DPM) emissions. The 5.6-L, six-cyUnder test engine 
is typical of types certifiable for use in underground mines. Test pcU"£imeters consisted of additive 
concentration and engine loads, speed, and air intake restriction. DPM emissions, including condensed 
volatiles, were measured gravimetrically. Also measured were gaseous emissions including carbon 
monoxide, nitrogen oxides, and hydrocarbons. 

The fuel additive was effective, reducing DPM up to 75 pet, when used at a concentration of 0.09 wt 
pet (one-fourth of the concentration recommended by the msmufacturer). The additive was most 
effective at the highest fuel-air ratios, reducing DPM from 400 mg/m' for untreated fuel to 120 mg/m^. 
At Ught loads, 25 pet of full rated, no DPM reductions were measured. Based on these results, the 
additive is recommended for use in diesel fuel, at a concentration of 0.09 wt pet, to power underground 
mining equipment as long as certain conditions are met: that a beneficial DPM reduction is verified, 
that the minimimi required quantity of additive is used, and that potential adverse effects such as 
increased nitrogen oxides are checked. 



^Physical scientist, Twin Cities Research Center, Bureau of Mines, Minneapolis, MN. 



INTRODUCTION 



Diesel-powered equipment is widely used in under- 
ground mining because of its high productivity potential 
and flexibility compared with electric-powered equipment. 
Unfortunately, diesel engines emit particulates consisting 
of insoluble carbonaceous agglomerates, adsorbed soluble 
organic compounds, and traces of other substances such as 
sulfates and metals. Although diesel particulate matter 
(DPM) levels are not specifically regulated in underground 
mines, DPM adds to the general dust level amd aggravates 
efforts to comply with respirable dust standards. 

To help mine operators comply with dust standards and 
to reduce potential occupational hezdth problems (1)^ 
arising from exposure to DPM emissions, the Bureau of 
Mines is conducting research on improved DPM control 
methods to supplement current controls such as ventila- 
tion, engine maintenance, and operator work practices. 
The emphasis, to date, has been on the evaluation of the 
diesel particulate filter (DPF) for coal and noncoal mines 
(2-3). However, even if successful, the DPF can be used 
on inby equipment in coal mines only as part of an inte- 
grated exhaust cooUng and filtering system, which is cur- 
rently still under development (3). 

To provide the mining industry with alternatives to the 
DPF, other DPM controls, such as fuel additives, are 
being evaluated by the Bureau. Additives can be classified 
according to the problems they are designed to correct. 
"Preflame" additives are designed to correct problems that 
occur prior to burning (that is, storage stability, flow in 
cold weather, water contamination) and include disper- 
sants, pour-point depressants, and emulsifiers. "Flame" 
additives promote complete burning of fuel in the com- 
bustion chamber and include atomizers and combustion 
catalysts. "Postflame" additives are designed to reduce 
engine deposits, smoke, and emissions. 



The Bureau selected a bcu^ium-based, postflame product 
because earUer research by others (4-6) generally con- 
cluded that barium was more effective for reducing diesel 
soot than fuel additives such as iron or calcium com- 
pounds. The additive tested is a commercial product, 
Lubrizol 565 (see appendix). Prior research on postflame 
fuel additives by the Bureau amd others was reviewed by 
ZeUer (7-8). 

The general objective of this work was to determine the 
effectiveness of a barium-based fuel additive for reducing 
DPM emissions. Specific objectives were as follows: (1) 
Determine the optimum additive concentration for mini- 
mum DPM emissions, (2) evaluate the effect of the addi- 
tive on individual components of engine exhaust, (3) de- 
termine the extent of amy adverse effects of the additive, 
and (4) compare the results with those from earlier tests 
on a different engine (7-8). 

In this report, the effects of the additive on DPM emis- 
sions are examined first. Then, effects on the following 
specific exhaust components are examined: (1) solid diesel 
particulate matter (SDPM), (2) volatile diesel particulate 
matter (VDPM), (3) gas-phase hydrocarbons (GPHC), and 
(4) total exhaust hydrocarbons (TEHC), which are defined 
as the sum of the VDPM and the GPHC in the exhaust. 
Both the volatile and gas-phase hydrocarbons are consid- 
ered because they contain the carcinogenic and mutagenic 
compounds that may have adverse health effects on work- 
ers exposed to diesel exhaust (1). The effects of the addi- 
tive on both carbon monoxide (CO) and nitrogen oxides 
(NOJ are zilso reported. Finally, the results for DPM 
emissions are compared with those from a different engine 
tested with the same additive. 



ACKNOWLEDGMENTS 



The author gratefully acknowledges the contributions 
of CcU"l Anderson, physical scientist, Twin Cities Research 
Center, who did the special programming required for 
the engine control system, and Robert G. Vandenbos, 



electronics technician. Twin Cities Research Center, who 
ensured the proper operation and calibration of the ex- 
haust emissions measuring instruments and associated data 
acquisition systems. 



APPARATUS AND PROCEDURES 



The Bureau's Diesel Emissions Research Laboratory 
consists of three adjoining rooms: the control room, the 

Ttalic numbers in parentheses refer to items in the list of references 
preceding the appendix at the end of this report. 



engine test cell, and the emissions room. Figure 1 shows 
the generzil layout of the laboratory and identifies the 
major hardware used or available for this study. Details of 
this facility have been published (7). 



KEY 

oooooooooo Diluted exhaust 

Dilution air 

************ Exhaust sample orifice 

Gas emissions sample 

Raw exhaust 



yw 



Signal 
condition 



^\ 



Controller 



Data 
logger 



Computer 



yw 



Fuel meter 



Engine 



;7 



Dynamometer 



Fuel 
tank 



— |— *— Opacity 



S 



Particulate 
filter 

A 



Pump 
Outside 



z 



._.fJLter__. 
Charcoal 



Dilution air 



CO 
HC 
NOx 



Control room 



Test cell 



Emissions room 



Figure 1. -Diesel engine emissions research laboratory. 



ENGINE TEST CONDITIONS 

Most of the results presented in this report were ob- 
tained from tests conducted on a Deutz^ F6L 912W six- 
cyhnder, four-cycle, diesel engine. Versions of this 
indirect-injected, naturally aspirated, air-cooled, 5.6-L 
engine are certified for underground coal mine use by the 
U.S. Mine Safety and Health Administration (MSPIA) 
and are rated for 82 hp at 2,300 r/min. The engine com- 
plied with factory specifications for power, fuel consump- 
tion, and gaseous emissions. For the purpose of compar- 
ing different engines, selected results from previous tests 
(7-8) on a Caterpillar 3304 engine are also presented. The 
Caterpillar engine is generally similar to the Deutz engine 
except that it is water cooled and has four cylinders instead 
of six. 



Reference to specific products does not imply endorsement by the 
U.S. Bureau of Mines. 



Engine loads were applied by an eddy-current universal 
dynamometer and were controlled by a microprocessor 
system that maintains precise speed (±1 r/min) and load 
(±0.1 pet). A data acquisition system recorded up to 
48 analog inputs from various transducers such as ther- 
mocouples and pressure transducers. 

All the tests were conducted at steady-state conditions. 
The engine was started and brought to normal operating 
temperature before any test sequence was begun. Changes 
in intake air density affect the fuel-air ratio to the extent 
that DPM emissions from some engines, operated at or 
near peak torque loads, can increase about 10 pet for each 
1 pet decrease in the air intake density (7). For this rea- 
son, controls on the engine intake system are used for 
maintaining air intake conditions. The manual temper- 
ature and automatic pressure controls can maintain engine 
air intake density to within ±0.5 pet of set values. 

Three air intake conditions or restrictions were adopted. 
At an air temperature of 77° F (25° C), the small, medium, 
and large intake restrictions are respectively equivalent to 



pressure drops into the engine of 8, 28, and 53 in HjO 
from 1 atm. In practice, both the temperature and pres- 
sure of the engine intake air were controlled to maintain 
air densities equivalent to the temperature-pressure com- 
binations Usted. Note that the small-restriction condition 
is equivalent to the Society of Automotive Engineers 
(SAE) (9) recommended power test conditions for dry air. 
All emissions data reported here are adjusted to SAE 
conditions of temperature and pressure. 

Engine exhaust back pressures are controlled by a com- 
bination of a butterfly valve and an exhaust fan. Most 
engine tests were conducted with only a few inches of 
water back pressure. A few tests were conducted at back 
pressures up to 40 in HjO, the engine manufacturer's rated 
maximxmi (10-11). 

FUEL, OIL, AND ADDITIVE MIXING 

All the tests were conducted with the same batch of 
No. 2-D fuel. No chemical analysis for this fuel is avail- 
able. The crankcase oil was SAE 30 weight and was 
changed at 100-h intervals. 



The additive was premixed, by weight, with the fuel in 
55-gal drums prior to testing. Between runs involving 
different fuel mixtures, the engine fueling system was 
drained to prevent fuel used in prior tests from influencing 
the results of subsequent tests. Any residual old fuel re- 
maining in the system after draining was purged by oper- 
ating the engine for at least 1 h using the new fuel mixture. 

EMISSIONS MEASUREMENT 

Approximately 3 pet of the raw exhaust was diluted and 
transported to the sampling section (fig. 1) where the 
DPM was collected on fluorocarbon-coated, glass-fiber 
filters. Dilution was always sufficient to maintain filter 
temperatures below 125° F. The volatile pzirticulate on the 
filters was determined gravimetrically jifter treatment in a 
vacuimi oven at a temperature of 392° F. Measurements 
of nitrogen oxides, carbon monoxide, and gas-phase hy- 
drocarbons were made on undiluted exhaust transported 
through a heated (350° F) Une (fig. 1). 



RESULTS AND ANALYSIS 



PARTICULATE EMISSIONS 

The two largest components of DPM are the soUd 
fraction, composed mainly of carbon and sulfate for un- 
treated fuels, and the volatile fraction, which is derived 
from fuel and engine lubricant. For barium-treated fuel, 
the solid DPM also contains barium compounds. In the 
following sections, the effects of engine operating param- 
eters on DPM are presented followed by an exeunination 
of the effects of barium on total DPM and on the two 
main fractions-solid and volatile. 



All the data in figures 2 and 3, plus additional results, 
are displayed more concisely in a single chart (fig. 4), 
plotting emissions against fuel-air ratio. Some of the 
scatter is caused by experimented error, but most of the 
observed spread is attributable to engine speed effects. 



Diesel Particulate Matter 
Untreated Fuel 

DPM emissions from diesel engines depend on many 
variables, including speed, torque or load, and air intake 
conditions. Figure 2 compares the average DPM mass 
concentration for the Deutz engine at four loads, one 
intake condition, and one speed. Other speed and intake 
conditions produce similar plots. Figure 2 shows that the 
lowest DPM concentrations (40 mg/m^) are measured at 
75 pet of full load jmd that lower or higher loads increase 
DPM. The maximum emission level (115 mg/m^) occurs 
at full load. 

DPM emissions are plotted for full-torque conditions at 
four speeds and three intake conditions (fig. 3). The over- 
all range of emissions is almost 7:1 (60 to 400 mg/m^). 
At fixed intake conditions, speed variations produce about 
a 3.5:1 range of DPM emissions, while at fixed speed, the 
intake conditions shown have about a 2:1 effect on the 
DPM emissions. 



120 



100 



80 



60 



40 



20 







25 



75 90 

ENGINE LOAD, pet 



100 



Figure 2.-DPM emissions from Deutz engine for untreated 
fuel, 2,300 r/min, and medium intalte restriction. 



500r- 



I 400- 

E 

Z 

9. 300h 

I- 
< 
d. 



z 

LU 

o 

z 
o 
o 



Q. 

D 



200- 



100- 



KEY 
Intake restriction, in H2O 
^ 8 (small) 
HI 28 (medium) 
□ 53 (large) 




65 80 90 100 



65 80 90 100 
ENGINE SPEED, pet 



65 80 90 100 



Figure 3.-DPM emissions from Deutz engine for untreated fuel, full load, four speeds, and three intake restrictions. 



500 



400- 



E 

I 300 

I- 
< 
tr 



LU 

^ 200 

O 
O 



a. 

Q 

lOOh 



0.01 







1 1 
KEY 


1 




1 






Intake 


restriction, in HjO 
^r..-nr^ll^ 






7 
/ 

/ 

/ 




_ 


A 


— 28 (medium) 






_ 


V — — — 


- 00 Uarge; 










9 


/ 












7/ 


// 




- 


9S^ 




1 


# 


1 


- 


1 1 



0.02 



0.03 0.04 

FUEL-AIR RATIO 



0.05 



0.06 



Figure 4.-DPM emissions from Deutz engine as function of fuel-air ratio for untreated fuel. 



For fuel-air ratios less than 0.04, the DPM emissions 
rjinge between 40 and 100 mg/m^ with minimum emis- 
sions measured for the fuel-air range between about 0.03 
and 0.035. The rapid increase in DPM emissions for fuel- 
air ratios greater than about 0.04 emphasizes the impor- 
tance of maintaining fuel-air ratios as low as possible. 
This can be accomplished by proper maintenance of the 
engine's air and fuel systems and by not lugging the 
engine. 

The mine ventilation required for certified engines of 
this type is 85 cfm/hp (10-11), which will dilute the exhaust 
by about 40:1. Applying this dilution factor to the mea- 
sured emissions (figs. 2-4) indicates that the in-mine DPM 
levels produced by this engine will range between 1 and 
10 mg/m^. It is clear that this engine can contribute sig- 
nificantly to mine dusts. 

Barium-Treated Fuel 

The data in figure 5, which were obtained from a Cat- 
erpillar engine (7), illustrate two important results of using 
barium-treated fuel: first, barium compounds represent a 
substantial fraction of DPM, especially at high additive 
concentrations in the fuel, and second, the non-barium 
fraction (carbon, sulfates, and volatiles) at each of the 
engine loads is nearly independent of additive concentra- 
tion, which suggests that the additive might effectively 
reduce DPM at even lower concentrations than the 0.18- 
wt-pct level shown. 

Experiments were conducted on the Deutz engine to 
determine the optimum concentration required to mini- 
mize DPM emissions. The results (fig. 6) are for additive 
concentrations between 0.0 and 0.36 wt pet, engine speeds 
of 90 and 100 pet of full-rated, engine torques from 25 to 
100 pet of full torque, and the medium intake restriction. 

Examination of these results leads to the following 
observations: (1) Even the minimum additive level tested, 
0.02 wt pet, reduced DPM levels, compared with untreated 
fuel, (2) the most effective concentration for minimum 
DPM emissions under the test conditions was 0.09 wt pet, 
(3) most of the results obtained for 0.18 and 0.36 wt pet at 
full engine speed indicate that these levels are too high 
because DPM emissions are greater than those for 0.09 wt 
pet. 

In order to better illustrate overall trends, DPM emis- 
sions are. plotted against fuel-air ratios in figure 7 for 
treated and untreated fuel (at different engine intake con- 
ditions, engine speeds, and engine loads). Comparing 
untreated-fuel results with those for the 0.09-wt-pct addi- 
tive level indicates that the barium additive is not useful at 
fuel-air ratios smaller than about 0.02. The effectiveness 
as measured by DPM reduction from the untreated-fuel 
condition cle£U"ly improves with increasing fuel-air ratio. 



Also, for fuel-air ratios between 0.03 and about 0.045, 
DPM emissions for the 0.09-wt-pct treatment do not ex- 
ceed 50 mg/m^ while DPM levels for untreated fuel range 
up to 250 mg/m^. Only at the highest fuel-air ratios 
tested do the results suggest that additive levels of 0.18 
jmd 0.36 wt pet may be slightly more effective than the 
0.09-wt-pct treatment. 

Solid Particulate Fraction 

The SDPM fraction is the material remaining on the 
sample filters eifter vacuum-oven treatment. The values of 
SDPM for untreated fuel (fig. 8) show how the soUd 
fraction, in this case mostly carbon and sulfates, increases 
uniformly with increasing fuel-air ratio. Because the con- 
tribution of volatiles to DPM at fuel-ciir ratios greater than 
0,03 is small, the SDPM and DPM emissions plots are 
similar at high fuel-air values. 

To illustrate the effect of barium treatment on the 
particulate soHds fraction, SDPM is plotted in figure 9 for 
one engine speed condition and three additive concentra- 
tion levels. By restricting the plot to one speed, the trends 
for each fuel condition are clearly delineated. These data 
emphasize that most of the SDPM reduction attributable 
to the additive occurs at high fuel-air ratios; for example, 
a 75-pct reduction (340 to 80 mg/m^) was obtained at the 
0.05 fuel-air ratio. No sohds reduction is observed for the 
lowest fuel-air ratios of about 0.016. 

Generally, the minimum SDPM levels were measured 
for an additive concentration of 0.09 wt pet. At some 
fuel-air ratios between 0.03 and 0.035, the 0.36-wt-pct 
additive concentration produced slightly greater emissions 
than those measured for untreated fuel. 

Volatile Particulate Fraction 

The VDPM mass concentration ranged from 60 mg/m^ 
at low fuel-air ratios to near zero at high fuel-air ratios 
(fig. 10). At fuel-air ratios less than 0.02, the minimum 
VDPM levels are for the lowest speed tested. This result 
agrees with that of others who found that, at light loads, 
lubricating oil emissions tend to increase with increasing 
engine speed (12). 

The full engine speed results (fig. 11) show that the 
barium-additive treatment results in reduced VDPM emis- 
sions. In a later section, "Hydrocarbon Emissions," it is 
shown that the gas-phase hydrocarbons are either un- 
changed or increased slightly with the fuel treatment. 
Consequently, it is suggested that the VDPM reduction is 
caused by the large SDPM reductions (fig. 9), which in 
turn reduce the particulate surface available for hydro- 
carbon adsorption and condensation. 



250 n 



200 



150 



E 



< 
cr 



S 100 

o 
o 



Q. 

Q 



50 - 



7 pet 



KEY 

Barium compounds 
Non-barium fraction 



^ 



^ 



18 0.36 0.72 



50 pet 



V77 



m 



90 pet 



^ 



0.18 0.36 0.72 0.18 0.36 0.72 

ADDITIVE CONCENTRATION, wt pet 



100 pet 



M 



0.18 0.36 72 



Figure 5. 
full load. 



Effect of barium fuel additive on DPM constituents from Caterpillar engine at 1,200 r/min and 7, 50, 90, and 100 pet of 



80 r 



60 - 



< 

cr 40 



20 







25 pet 



•SPEED, 90 pet- 
90 pet 







) 


. 


\ 



100 pet 



M 



w^ 



■SPEED, 100 pet - 
100 pet 



m W^': 



Wawm 



02 0.045 0.06 09 0.02 0.045 0.06 0.09 0.02 0.045 06 09 0.06 0.09 0.18 0.36 

ADDITIVE CONCENTRATION, wt pet 
Figure 6.-Effect of additive concentration on DPM emissions from Deutz engine at two speeds and 25, 90, and 100 pet of full load. 



500 



400 



E 



< 

DC 



o 

z 
o 
o 

a. 

Q 



300- 



200- 



100- 





1 1 

KEY 


1 1 


1 






Additive, wt pet 










D 0.00 
A 0.09 
V 0.18 
0.36 




D 
D 




- 




D 


D 


- 


- 




a 

n 




- 


_ 




cP 


A 


_ 




E 

1 1 


1 1 


1 





0.01 



0.02 0.03 0.04 

FUEL-AIR RATIO 



0.05 



0.06 



Figure 7.-Additive effect on DPM emissions from Deutz engine at different fuel-air ratios. 



E 

z 
O 

(- 
< 
fX. 



UJ 

o 

z 
o 
o 

CO 
CO 

< 



500 



400 



300 



200 



a. 

Q 

CO 100 



Ol — 
0.01 



KEY 
Engine speed, r/min 
o 1,500 
A 1,840 
V 2,060 
O 2,300 



TS" 



0.02 




_L 



_L 



0.03 0.04 

FUEL-AIR RATIO 



0.05 



0.06 



Figure 8.-SDPM emissions from Deutz engine for untreated fuel. 



400 




0.01 



0.02 



0.03 0.04 

FUEL-AIR RATIO 



0.05 



0.06 



Figure 9.-Additlve effect on SDPM emissions from Deutz engine at 80 pet of rated speed. 



en 

E 



< 

DC 



LU 

o 

z 
o 
o 

CO 

< 



a. 

Q 

> 



ou 


1 


1 






1 


1 
KEY 






^Ov 








E 


ngine speed, r/min 






A 










□ 1,500 














A 1,840 






^ 










V 2,060 






A 










O 2,300 




40 


D 

D 
D 










D 




20 


- 








a 




- 


n 


1 


O 
A 
V 

1 


D 

D 

A 



D 

O 

A 
A 

V 


o 

V 


O 
A O 

a 

A 
n lA 





0.01 



0.02 



0.05 



0.03 0.04 

FUEL-AIR RATIO 
Figure 10.-VDPM emissions from Deutz engine for untreated fuel. 



0.06 



10 



E 



< 

cc 



LU 

o 

z 
o 
o 
CO 

C/5 
< 



a. 

Q 
> 




0.03 
FUEL-AIR RATIO 



0.05 



Figure 11. -Additive effect on VDPM from Deutz engine at full speed. 



Comparison of Solid and Volatile Fractions 

The results (fig. 12) for full engine speed and the small 
intake restriction were selected to illustrate the relative 
levels of the solid and volatile particulate components for 
both treated and untreated fuels. For the Deutz engine 
and for both treated and untreated fuel, the solid fraction 
(SDPM) is the main component of DPM for fuel-air ratios 
greater than about 0.025, while at smaller fuel-air ratios 
the volatile fraction (VDPM) is the main constituent of 
DPM. The most obvious effect of the additive is reduction 
of the solid component, although, as noted in previous 
sections, some volatile reduction also occurs. 

Also (fig. 12), for treated fuel (0.09 wt pet), the nearly 
constant level of SDPM between 30 and 40 mg/m^, in 
conjunction with the results in figure 6, suggests a mini- 
mum DPM level and maximum effectiveness of DPM 
reduction using barium. At full load, the barium rate 
into the engine, for 0.09-wt-pct additive in the fuel, is 
52 mg/min. If all the barium is emitted as barium sulfate 
(7) in the exhaust, the concentration is about 25 mg/m^, 
the major portion of the SDPM emitted. There are other 
unknown substances in this commercial additive that may 
also be emitted as solid components in the exhaust. The 
point is that the composition of the additive may be a 
significant limiting factor in DPM reduction; therefore, it 
is important to use only sufficient additive to achieve the 
required or desired effectiveness. 



200 



KEY 

Emission, treatment 



150 



DPM, untreated 
SDPM, untreated 
SPDM, 0.09 wt pet 
VDPM, untreated 
VDPM, 0.09 wt pet 



100 




0.03 
FUEL-AIR RATIO 



05 



Figure 12.-Comparison of solid and volatile particulates from 
Deutz engine at full speed for small intake restriction. 



11 



HYDROCARBON EMISSIONS 
Gaseous Hydrocarbons 

The untreated-fuel GPHC mass concentration emissions 
are plotted (fig. 13) for all test conditions. The range of 
GPHC concentrations (plotted as methane equivalent) is 
large-between 10 and 80 mg/m^. There will be no at- 
tempt to identify trends, because of the complex inter- 
actions among engine speed, engine load, and engine in- 
take conditions. An additional complicating factor is the 
probability that a substantial fraction of the GPHC orig- 
inates from the engine lubricating oil, especially at light 
loads and high speeds (12). 

GPHC emissions for both treated and untreated fuels 
are plotted in figure 14, where the untreated-fuel data are 



the same as those plotted in figure 13. It is apparent that 
the main effect of the additive is to reduce the overall 
range of the GPHC emissions, especially at fuel-air ratios 
greater than 0.025. The minimum GPHC level observed 
for treated fuel is about 25 mg/m^, compared with the 
minimum of about 10 mg/m^ observed for untreated fuel. 
The increase in GPHC for treated fuel can be explained by 
referring back to figure 11, which showed that the con- 
densed volatiles, or VDPM, were decreased, on the aver- 
age, by barium-treated fuel. Consequently, it follows that 
if the exhaust hydrocarbons do not condense on the par- 
ticulate fraction, then they must remain in the gas phase as 
observed. What is not explained is why the GPHC levels 
for treated fuel (fig. 14) decrease with increasing additive 
concentration. Additive effects on exhaust hydrocarbons 
are examined further in the following section. 



ou 


1 
V 


1 


1 


1 
KEY 






V 




Engi 


ne speed, r/min 
A 1,500 




^ 60 


aO 






V 1,840 










O 2,060 


- 


E 


D 






□ 2,300 




2f 


O 










o 


A 










1- 












< 


„o 






o 




a: 

1- 


V 


O V 








2 












uj 40 
O 


" A ° 


O V 




7 


— 


z 




v: s 


($> 


V A A 




o 




D 


V 




o 




V 


g 




w 


O 


A A '^ 




i-i 




< 




A 


°A A 


A 




2 








D 




^ 20 


- 


D 






- 


Q. 
(5 




O 


a 
o 


O 







1 


1 


1 


1 





0.01 



0.02 



0.03 0.04 

FUEL-AIR RATIO 



0.05 



0.06 



Figure 13.-GPHC concentrations (plotted as methane equivalent) from Deutz engine for 
untreated fuel. 



12 



ou 


1 


1 
A D 


1 1 1 
KEY 








D 


Additive, wt pet 








V 


D 0.00 




n 




O 


A 0.09 




t 60 


_ 


CP 


V 0.18 


_ 


E 






O 0.36 




z 




^ 






o 





D 






h- 








< 




□ ° 


^ ^ 




1- 

1 40 


V 


n ° 




_ 


z 




□ 


O^D A „ D V 




O 

o 


A 








CO 
CO 

< 

5 




D 




^ 20 







D 
D 


_ 


Ql 










o 


1 


1 


1 1 1 





0.01 



0.02 0.03 

FUEL-AIR RATIO 



0.04 



0.05 



0.06 



Figure 14.-GPHC concentrations (plottecJ as methane equivalent) for different additive 
concentrations and for all Deutz engine conditions. 



Total Exhaust Hydrocarbons 

Diesel exhaust is a complex, dynamic system in which 
the physical and chemical properties of the species present 
continuously change with time. For the purpose of this 
discussion, the following are assumed: (1) The diluted 
exhaust, from which the filter sample is extracted, is rep- 
resentative of the state of the VDPM in the exhaust pipe; 
that is, adsorption, desorption, and condensation are fully 
quenched at the instant of dilution; (2) the heated gas 
sampling line provides a representative GPHC sample to 
the instruments. If these conditions are met, then an 
estimate of TEHC is determined as follows: 

TEHC - VDPM + GPHC, 

when expressed in consistent units such as mass 
concentration. 

Calculated values of TEHC are plotted (fig. 15) against 
fuel-air ratio. No strong trends are apparent. Of more 
interest are the treated-fuel levels of TEHC for full-speed 
conditions (fig. 16) along with untreated-fuel data also for 
full-speed conditions; all three intake conditions are plot- 
ted here. There are two observations. First, the average 
TEHC levels do not appear to be substantially changed 
when all treated-fuel results are compared with all 
untreated-fuel data. Additive effects on TEHC are not 



significant relative to the reductions measured for SDPM 
(fig. 9). On the other hand, looking only at the treated- 
fuel results, TEHC levels appear to decrease with increas- 
ing additive concentration, as a result of the decrease in 
GPHC levels with increasing barium concentration. 

TOXIC GASEOUS EMISSIONS 

Nitrogen Oxides 

Nitrogen oxide emissions for different speeds, loads, 
intake restrictions, and additive treatments are plotted 
against fuel-air ratio (fig. 17). In general, nitrogen oxide 
formation increases with temperature and with the avail- 
ability of oxidizing agents during combustion. For exam- 
ple, combustion temperature is related directly to fuel-air 
ratio and in-cylinder oxygen concentration is related in- 
versely to fuel-air ratio. As a result, some of the nitrogen 
oxide emission plots (fig. 17) peak at about a fuel-air ratio 
of 0.04. 

For untreated fuel, the lowest nitrogen oxide levels of 
about 100 mg/m^ were measured for the largest restriction 
(minimum oxygen) and low fuel-air ratios corresponding 
to minimum temperatures. The highest levels for un- 
treated fuel, around 800 mg/m^ were for the smallest 
intake restriction (higher oxygen levels) and high fuel-air 
ratios (high temperatures). 



E 



< 



LU 

o 

z 
o 
o 

CO 
CO 

< 



o 

X 
LJJ 



150 



100 



50- 



0.01 



xP o 

V 

. n 



13 



KEY 

Engine speed, r/min 

D 1,500 
A 1,840 
V 2,060 
O 2,300 



O 

V 



^ 



^ 



A O 

07. 



O 

D 



O 

D 

A 

A 
D V 

D 



0.02 



0.03 0.04 

FUEL-AIR RATIO 



0.05 



0.06 



Figure 15.-TEHC concentrations for untreated fuel and all Deutz engine conditions. 



E 

2f 

o 

I- 
< 
cc 

h- 

z 

UJ 

o 

z 
o 
o 

CO 

CO 
< 



o 

X 
LU 





1 


1 


1 


1 1 

KEY 












Adciitive, wt pet 








^D 




D 0.00 
A 0.09 








n^ 




V 0.18 








% 




o 0.36 




100 


- 






- 






C^ 












A 












cn 












D 




V 




50 


> < 

1 


1 


D 

1 


mA D o Aq 

D ° 
1 1 





0.01 0.02 0.03 0.04 

FUEL -AIR RATIO 



0.05 



0.06 



Figure 16.-TEHC concentrations from Deutz engine for treated fuel at full speed. 



14 



E 

2 

O 
I- 
< 

DC 



LU 

o 

z 
o 
o 

CO 

CO 
< 



,uuu 


1 




1 


1 


1 
O 


1 






KEY 








o 








Restriction. 


Additive. 




O 


o 








in HjO 


wt pet 




n 


■ * 






800 


D 8 " 






D . D '-' 

'^ n n o 

A V«D A?^ 




_ 




A 28 • 
V 53. 
■ 8' 





D 








▲ 28 ■ 


0.09 


Oa 


% ^ 


D 


\l " 






▼ 53. 




% 




▼ 




600 


~ O 8 


0.36 


& 


A ^ 


A 


- 








A 


▼ 














V 




A 


A 










D 


A 


A 










OA 












400 


■ 


A 
A 


A 
A 


A 


V 
V 






200 


1 


A 


V 

1 


1 


1 


1 





0.01 0.02 0.03 0.04 

FUEL-AIR RATIO 



0.05 



0.06 



Figure 17.-Comparison of nitrogen oxide concentrations from Deutz engine for treated and 
untreated fuels. 



Overall, the treated-fuel nitrogen oxide levels were 
greater than those measured for untreated fuel at the same 
fuel-air ratios. The 0.36-wt-pct additive treatment and 
small restriction produced the highest nitrogen oxide levels 
for a given fuel-air ratio. This general increase in nitrogen 
oxide levels for treated fuels is assumed to be the result of 
the oxidizing effect of barium. These results again empha- 
size the importance of not using any more additive in the 
fuel than necessary for DPM reduction. 

Carbon Monoxide 

The carbon monoxide exhaust emissions are plotted 
(fig. 18) against fuel-air ratio. The effect of the additive 
on carbon monoxide levels is mixed, which suggests that 
the additive will produce neither positive nor negative 
effects on carbon monoxide in the exhaust. 

ENGINE COMPARISON 

The purpose of this section is a limited comparison of 
the DPM emissions from two different engines: the Deutz 
engine tested in this research and a Caterpillar 3304 



engine evaluated earlier (7-8). The comparison is limited 
because test data for the Caterpillar engine are available 
only for low-speed tests at 1,200 r/min or 67 pet of the 
full-rated speed (1,800 r/min) for that engine. 

The DPM emissions for untreated fuel (fig. 19) are 
expressed in power-specific mass rate to help account for 
the differences in the test loads and speeds for the two 
engines. Over the full range of fuel-air ratios, the Cat- 
erpillar engine emissions are smaller than those from the 
Deutz engine, including the full-speed Deutz engine data. 

DPM emissions are shown in figure 20 for a fuel treat- 
ment of 0.18 pet (the smallest concentration data avail- 
able for the Caterpillar engine) for both engines, plus 0.09- 
wt-pct additive results for the Deutz engine. The data 
show that for treated fuel the Deutz engine emits less 
DPM at most fuel-air ratios. In other words, the additive 
appears to be more effective for the Deutz engine, with 
the qualification that this result may be related to the 
fact that the speed of the Deutz engine was greater- 
1,840 r/min (80 pet of full-rated speed) compared with 
1,200 r/min for the Caterpillar engine (67 pet of full-rated 
speed). If the two engines could be compared at the same 
speeds, the results might be different. 



15 



500 



400- 



E 

I 300 

< 
tr. 



UJ 

o 

z 
o 
o 

o 
o 



200- 



100 





1 


KEY 


1 


1 1 


1 






Restriction, 


Additive. 










in HjO 




wt pet 










D 8 " 
A 28 




0.00 




▼ 

A 






V 53 

A 28 \ 
T 53 J 




0.09 


V 

A 

V 










■ 
A^ 

67 




V 

A 
DA 

°A 


V 




- 


■ 
1 


8^ 

D 
D 


D 

1 


1 1 


1 


- 



0.01 0.02 0.03 0.04 

FUEL-AIR RATIO 



0.05 



0.06 



Figure 1 8.-Comparison of carbon monoxide concentrations from Deutz engine for treated and 
untreated fuels. 



10 



25 



20 



P 15 - 



Q 10 



1 1 

I 

Ia 






1 

KEY 

D Caterpillar 


1 




^ 






A Deutz 




'. ^ 








f 
f 












^ 




a\ 






a/ 




\a 








f 

1 




A 






/ 

/ 

A/ 


D 


- 


j ^ \ 






/ 
/ 

^ / 


J 


/ 


P A \ 






/ 
/ 


/ 




\ \ 






A / ^ 


/ 


a ~ 


\ \ 






'A. / 


















\ \ 






/a X 






\^ \^ 






A / jf 










A 


* t^ 






1 1 


— 5 


f 


0^ ° 

1 


1 





0.01 



0.02 



0.03 0.04 

FUEL-AIR RATIO 



0.05 



0.06 



Figure 19.-Comparison of DPM from Deutz and Caterpillar 
engines for untreated fuel. 



0.02 



KEY 

□ Caterpillar 
A Deutz 




-^ 



r^i- ' 



_L. 



0.03 



0.04 
FUEL-AIR RATIO 



0.05 



0.06 



Figure 20.-Comparison of DPM from Deutz and Caterpillar 
engines for treated fuel. 



16 



CONCLUSIONS AND RECOMMENDATIONS 



At fuel-air ratios between 0.01 and 0.052, the DPM 
emissions of the Deutz engine ranged between 35 and 
420 mg/m^. For fuel-air ratios up to about 0.04, the 
maximum DPM levels measured were less than about 
120 mg/m^, a result that emphasizes the importance of 
operation at high speed with minimum intake restrictions 
(clean air filters) in order to maintain low fuel-air ratios. 

The DPM emissions from the Deutz engine were com- 
pared with those from a Caterpillar engine. For 
untreated-fuel operation, the DPM levels from the Cater- 
pillar engine were less than those from the Deutz engine 
over the entire range of fuel-air ratios tested. 

For maximum DPM reduction over the entire range of 
fuel- air ratios, the most effective additive concentration 
evaluated was 0.09 wt pet. Only at the maximum fuel-air 
ratios tested did the manufacturer's recommended concen- 
tration of 0.36 wt pet seem to impart a marginal additional 
benefit in reducing DPM compared with the 0.09-wt-pct 
treatment. Additive concentrations as low as 0.02 wt pet 
were observed to produce some DPM reductions. 

The effect of the additive on nitrogen oxide and carbon 
monoxide emissions was complex. Overall, nitrogen oxide 
levels tended to increase while carbon monoxide levels 



remained within the xmtreated-fuel range. Because emis- 
sion levels of both these gases are well within acceptable 
limits for the tested conditions and because the changes 
are small, the effect of the additive on nitrogen oxide 
should be considered in mine applications but is not ex- 
pected to be a problem for well-maintained engines and 
properly ventilated mines. 

This barium-based additive is recommended for re- 
ducing DPM emissions from diesel-powered equipment 
used in xmderground mines if the following conditions are 
met: 

1. The additive reduces excessive particulate levels 
and is used mainly in equipment having heavy work-duty 
cycles involving substantial periods of full or near-full 
load operation. 

2. The additive is used at the minimum concentration 
required to produce the measured DPM reduction ob- 
served. Based on results in this report, the suggested 
concentration is 0.09 wt pet. 

3. Potential adverse effects such as unacceptable nitro- 
gen oxide increases should be checked. 



REFERENCES 



1. National Institute for Occupational Safety and Health. 
Carcinogenic Effects of Exposure to Diesel Exhaust. U.S. Dep. Health 
and Hum. Serv., Public Health Serv., Curt. Intelligence Bull. 50, 1988, 
30 pp. 

2. Baumgard, K. J., and K. L. Bickel. Development and 
Effectiveness of Ceramic Diesel Particle Filters. Paper in Diesels in 
Underground Mines. Proceedings: Bureau of Mines Technology 
Transfer Seminar, Louisville, KY, April 21, 1987, and Denver, CO, 
April 23, 1987. BuMines IC 9141, 1987, pp. 94-102. 

3. Waytulonis, R. W., and G. Dvorznak. New Control Technology 
for Diesel Engines Used in Underground Coal Mines. Paper 42 in 
Proceedings of the 3rd Mine Ventilation Symposium (Oct. 12-14, 1987, 
University Park, PA). Soc. Min. Eng. AIME, 1987, pp. 279-285. 

4. Truex, T. J., W. R. Pierson, D. E. McKee, M. Shlef, and R. E. 
Baker. Effects of Barium Fuel Additive and Fuel Sulfur Level on 
Diesel Particulate Emissions. Environ. Sci. and Technol., v. 14, No. 9, 
1980, pp. 1121-1124. 

5. Kittleson, D. B., D. Dolan, R. B. Diver, and E. Aufderheide. 
Diesel Exhaust Particle Size Distributions-Fuel and Additive Effects. 
Sec. in The Measurement and Control of Diesel Particulate Emissions. 
SAE/PT-79/17, 1979, pp. 233-244. 

6. Hare, C. T., and K. J. Springer. Fuel and Additive Effects on 
Diesel Particulate Development and Demonstration of Methodology 



(Pres. at Automot. Eng. Congr. and Expo., Detroit, MI, Feb. 23-27, 
1976). SAE Tech. Paper 760130, 1976, 29 pp. 

7. Zeller, H. W. Effects of Barium-Based Additive on Diesel 
Exhaust Particulate. BuMines RI 9090, 1987, 40 pp. 

8. . Measurement of the Effects of a Fuel Additive on Diesel 

Soot Emissions. Paper in Diesels in Underground Mines. Proceedings: 
Bureau of Mines Technology Transfer Seminar, Louisville, KY, 
April 21, 1987, and Denver, CO, April 23, 1987. BuMines IC 9141, 
1987, pp. 79-93. 

9. Society of Automotive Engineers (Warrendale, PA). SAE 
Handbook: Engines, Fuels, Lubricants, Emissions, and Noise. V. 3, 
1982, p. 24.10. 

10. Sauerteig, J. E., and G. Perkuhn. Influence of Maintenance on 
the Exhaust Emission Quality of Diesel Engines. Paper in Diesel Use 
Seminar. Am. Min. Congr., 1988, pp. 118-144. 

11. MWM Diesel, Inc. (Norcross, GA). MWM Mining Engines. 
Bull. 662, Feb. 1986, 10 pp. 

12. Mayer, W. J., D. C. Lechman, and D. L. Hilden. The 
Contribution of Engine Oil to Diesel Exhaust Particulate Emissions. 
SAE Tech. Paper 800256, 1980, pp. 247-256. 



17 



APPENDIX.-ADDITIVE SPECIFICATIONS 

Supplier: 

Lubrizol Corp. 
29400 Lakeland Blvd. 
Wickliffe, OH 44092 

Type: Lubrizol 565 

Recommended concentration: 0.36 wt pet or 0.25 vol pet (or 1,075 lb per 1,000 barrels of fuel) 

Physical and chemical properties: 

Specific gravity at 60° F 1.22 

Viscosity at 100° C cSt . . 9.62 

Barium content wt pet . . 20-25 

Sulfur content wt pet . . 0.25-0.50 

Nitrogen content wt pet . . 0.4-0.6 



INT.BU.OF M1NES,PGH.,PA 29072 



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